Wieprzewski primarily dubs character voices, including many Hanna-Barbera characters such as Hardy Har Har on Lippy the Lion, Mr. Twiddle on Wally Gator, Dick Dastardly on Dastardly and Muttley, and the Creature King on Space Ghost. Wieprzewski is the Polish voice of Piglet in the Winnie the Pooh series, Gargamel on The Smurfs, Meowth in the Pokémon franchise, Dr. Doom on The Fantastic Four, Toad on The Wind in the Willows, and the puppet frog Kulfon in multiple Polish TV series. In animated features and specials, he dubbed the Winter Warlock in Santa Claus is Coming to Town, the skull and cat in The Last Unicorn, Doc and Fergus in Rango, and Rumpelstiltskin in Shrek Forever After.